The queries I find myself switching to Google for are:

* When I want a local result (i.e. I'm googling for business cards, and I want a UK based company that will sell them to me). This is because DuckDuckGo doesn't use your location (by default).

* When I am searching for a word that means something different to me than for the general population. For instance when I search for Python I don't want to see snakes. Google does this by tracking the results you click and forming a profile of you.

I guess the DuckDuckGo way is to search these by !uk and !programming, but that is a whole extra word to type. It would be nice if it let you list your interests in its settings page, creating your own filter bubble.

I wonder if this could be solved by creating fake personas, like "computer geek", or "professional programmer".

You opt into one or few of this personae and each query sent to a search engine would track this persona.

The key is that these categories should be few and predefined (i.e. offered by the search engine) so that they cannot be used to track individual users.